Bug 21174: Removed MSG_IN_YOUR_CART and its usage in OPAC JS

Bug 21174: Removed MSG_IN_YOUR_CART and its usage in OPAC JS

The 'Items in your cart' message is obsolete with the cart dropdown
box being removed.

Therefore the assignment of this text into the
MSG_IN_YOUR_CART variable (which is done in the opac-bottom.inc), and
the use of the MSG_IN_YOUR_CART variable in the updateBasket() function
(in the OPAC's basket.js) has been removed.

Sponsored-By: Toi Ohomai Institute of Technology, New Zealand
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>